Prototype-mean MiniLM beat keyword rules on our 30-intent router — Acc@1 0.87 + OOS recall 1.0

Author 30 intents × holdout (seed 20260928, API $0). Compared keyword rules vs MiniLM label-NN vs prototype-mean NN vs SetFit templated zero-shot. Not an Agent SDK surface. method Acc@1 macro-F1 OO